remove useless on_flame_remove_at function to fix servercrash on dig

nodes.lua

@@ -546,12 +546,6 @@ minetest.register_node("caverealms:constant_flame", {
 			fire.on_flame_add_at(pos)
 		end
 	end,
-	
-	after_dig_node = function(pos, oldnode, oldmetadata, digger)
-		if not (minetest.get_modpath("moontest")) then
-			fire.on_flame_remove_at(pos)
-		end
-	end,
 })
 
 --node to create a treasure chest in DM Forts.